Fatal error: Uncaught Error: Interface "Sabre\CalDAV\ICalendarObjectContainer" not found in /users/forscher/www/Baikal/vendor/sabre/dav/lib/CalDAV/Schedule/IInbox.php:15 Stack trace: #0 {main} thrown in /users/forscher/www/Baikal/vendor/sabre/dav/lib/CalDAV/Schedule/IInbox.php on line 15